Electron Mass, Charge, Rest Energy, and Localization from a Single Spacetime Mode

The electron mass, elementary charge, and rest energy are known experimentally with extraordinary precision, yet they remain empirical input parameters of the Standard Model rather than quantities calculated from a more fundamental structure. In Trembling Spacetime Relativity (TSRT), these observables are determined from a single stable localized mode of admissible oscillatory spacetime geometry. The construction begins from a primitive coherent Bessel-cell configuration and applies a controlled hierarchy of admissible boundary refinements. The same localized mode then determines the electron rest energy and inertial mass through its finite oscillatory energy closure, while the elementary charge follows from its invariant phase circulation and associated compact U(1)-type holonomy. The resulting values agree closely with experiment and are obtained without introducing the measured electron mass or charge as independent particle parameters. The mode possesses finite internal geometric support while remaining operationally pointlike at currently accessible experimental scales. The complete derivations, refinement hierarchy, numerical implementation, and convergence analysis are presented in the companion technical paper deposited on HAL. The present article summarizes the principal result: within TSRT, the defining electron constants arise as complementary observables of one localized spacetime-geometric structure.